Chemically functionalized renewed rubber composition

ABSTRACT

The renewed rubber of this invention can be used in rubber formulations that are used in manufacturing a wide array of rubber products, including tires, power transmission belts, conveyor belts, hoses, and a wide array of other products. The present invention more specifically discloses a method for manufacturing an environmentally friendly, chemically functionalized, renewed rubber composition having a highly desirable combination of physical properties and which exhibits excellent processability comprising the steps of (1) blending a micronized rubber powder with a processing aid and a chemical functionalizing agent to produce a blended mixture; (2) processing the blended mixture under conditions of high shear and low temperature to produce a reacted mixture; (3) adding a stabilizer to the reacted mixture to produce the chemically functionalized renewed rubber composition.

This is a divisional of U.S. patent application Ser. No. 14/694,447,filed on Apr. 23, 2015, which claims the benefit of U.S. ProvisionalPatent Application Ser. No. 61/986,696 filed on Apr. 30, 2014, U.S.Provisional Patent Application Ser. No. 62/063,801 filed on Oct. 14,2014, and U.S. Provisional Patent Application Ser. No. 62/105,024 filedon Jan. 19, 2015, is claimed hereby. The teachings of U.S. patentapplication Ser. No. 14/694,447, U.S. Provisional Patent ApplicationSer. No. 61/986,696, U.S. Provisional Patent Application Ser. No.62/063,801, and U.S. Provisional Patent Application Ser. No. 62/105,024are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to methods of using reclaimedcross-linked elastomeric material (thermoset polymers) and, inparticular, to methods of chemical functionalization of reclaimedelastomeric materials, such as micronized rubber powder and to elastomercompounds and compositions comprising the chemically functionalizedelastomeric materials.

BACKGROUND OF THE INVENTION

Millions of used tires, hoses, belts and other rubber products arediscarded annually after they have been worn-out during their limitedservice life. These used rubber products are typically hauled to a dumpor burnt as fuel because there is very little use for them after theyhave served their original intended purpose. A limited number of usedtires are utilized in building retaining walls, as guards for protectingboats and similar things where resistance to weathering is desirable.Some tires are ground into powder form to be used in variousapplications, such as tire compounds, binders for asphalt, mulch andsports field applications, to name a few. However, a far greater numberof tires, hoses and belts are simply discarded or burnt.

The recycling of cured rubber products has proven to be an extremelychallenging problem. This problem associated with recycling cured rubberproducts (such as, tires, hoses and belts) arises because, in thevulcanization process, the rubber becomes crosslinked with sulfur. Thesulfur crosslinks are very stable and the vulcanization process isextremely difficult to reverse. After vulcanization, the crosslinkedrubber becomes thermoset and cannot easily be reformed into otherproducts. In other words, the cured rubber cannot be melted and reformedinto other products like metals or thermoplastic materials. Thus, curedrubber products cannot be simply melted and easily recycled into newproducts.

Since the discovery of the rubber vulcanization process by CharlesGoodyear in the nineteenth century, there has been interest in therecycling of cured rubber. A certain amount of cured rubber from tiresand other rubber products is shredded or ground to a small particle sizeand incorporated into various products as a type of filler. Forinstance, ground rubber can be incorporated into asphalt for surfacingroads or parking lots. Small particles of cured rubber can also beincluded in rubber formulations for new tires and other rubber products.However, it should be understood that the recycled rubber serves only inthe capacity of a filler because it was previously cured and does notbond to an appreciable extent to the virgin rubber in the rubberformulation. Therefore, recycled rubber is typically limited to lowerloadings due to poor compound processing (compounds become more viscouswith higher loadings) as well as higher loadings leading to unacceptablecure properties.

Various techniques for devulcanizing cured rubber have been developed.Devulcanization offers the advantage of rendering the rubber suitablefor being reformulated and recured into new rubber articles if it can becarried out without degradation of the rubber. In other words, therubber could again be used for its original intended purpose. However,none of the devulcanization techniques previously developed has provento be commercially viable at high loadings. For example, somedevulcanized materials may be used at loadings of 3-5%. However, abovethis level the properties of the new rubber article are diminished. Thisis unsuitable for high performance applications, such as rubbercompounds for vehicle tires. In other cases, the devulcanized materialsare unsuitable for processing at high loadings into rubber compounds.These processing challenges can include short cure times (scorch), toolittle tack, too high viscosity, and poor mill handling and extrusionquality. A renewable material that can be used in high performanceapplications at loadings of 5% and higher is needed.

U.S. Pat. No. 4,104,205 discloses a technique for devulcanizingsulfur-vulcanized elastomer containing polar groups which comprisesapplying a controlled dose of microwave energy of between 915 MHz and2450 MHz and between 41 and 177 watt-hours per pound in an amountsufficient to sever substantially all carbon-sulfur and sulfur-sulfurbonds and insufficient to sever significant amounts of carbon-carbonbonds.

U.S. Pat. No. 5,284,625 discloses a continuous ultrasonic method forbreaking the carbon-sulfur, sulfur-sulfur and, if desired, thecarbon-carbon bonds in a vulcanized elastomer. Through the applicationof certain levels of ultrasonic amplitudes in the presence of pressureand optionally heat, it is reported that cured rubber can be brokendown. Using this process, the rubber becomes soft, thereby enabling itto be reprocessed and reshaped in a manner similar to that employed withpreviously uncured elastomers.

U.S. Pat. No. 5,602,186 discloses a process for devulcanizing curedrubber by desulfurization, comprising the steps of: contacting rubbervulcanizate crumb with a solvent and an alkali metal to form a reactionmixture, heating the reaction mixture in the absence of oxygen and withmixing to a temperature sufficient to cause the alkali metal to reactwith sulfur in the rubber vulcanizate and maintaining the temperaturebelow that at which thermal cracking of the rubber occurs, therebydevulcanizing the rubber vulcanizate. U.S. Pat. No. 5,602,186 indicatesthat it is preferred to control the temperature below about 300° C., orwhere thermal cracking of the rubber is initiated. Toluene, naphtha,terpenes, benzene, cyclohexane, diethyl carbonate, ethyl acetate,ethylbenzene, isophorone, isopropyl acetate, methyl ethyl ketone andderivatives thereof are identified as solvents that can be used in theprocess disclosed by this patent.

U.S. Pat. No. 6,548,560 is based upon the discovery that cured rubbercan be devulcanized by heating it to a temperature of at least about150° C. under a pressure of at least about 3.4×10⁶ Pascals in thepresence of a solvent selected from the group consisting of alcohols andketones having a critical temperature within the range of about 200° C.to about 350° C. The molecular weight of the rubber can be maintained ata relatively high level if the devulcanization is carried out at atemperature of no more than about 300° C. This devulcanization techniqueis reported to not significantly break the polymeric backbone of therubber or to change its microstructure. In other words, the devulcanizedrubber can be recompounded and recured into useful articles insubstantially the same way as was the original (virgin) rubber. Thispatent more specifically reveals a process for devulcanizing curedrubber into devulcanized rubber that is capable of being recompoundedand recured into useful rubber products, said process comprising (1)heating the cured rubber to a temperature which is within the range ofabout 150° C. to about 300° C. under a pressure of at least about3.4×10⁶ Pascals in the presence of a solvent selected from the groupconsisting of alcohols and ketones, wherein said solvent has a criticaltemperature which is within the range of about 200° C. to about 350° C.,to devulcanize the cured rubber into the devulcanized rubber therebyproducing a slurry of the devulcanized rubber in the solvent; and (2)separating the devulcanized rubber from the solve.

U.S. Pat. No. 5,770,632 discloses a process for reclaiming elastomericmaterial from elemental sulphur-cured elastomeric material having avulcanized network without using hexamethylene tetramine, by treatingthe sulphur-cured elastomeric material having a vulcanized network withone or more rubber delinking accelerators selected from the group ofzinc salts of thiocarbamates and zinc salts of dialkyl dithiophosphates,2-mercaptobenzothiazole or derivatives thereof, thiurams, guanidines,4,4′-dithiomorpholine and sulphenamides, and a zinc oxide activator inan amount sufficient to act as an activator for the accelerator(s) todelink the elastomeric material at a temperature below 70° C., wherebythe vulcanized network is opened up or delinked to provide a curablereclaimed elastomeric material capable of being vulcanized withoutadding rubber vulcanizing chemicals. The technique described in thispatent also includes compositions capable of delinking the vulcanizednetwork of sulphur-cured elastomeric materials including theaccelerators and activator described above. The obtained recycled, orreclaimed, elastomeric material has desired physical and dynamiccharacteristics that render it suitable for use in molded goods or foradmixture with fresh compounds in tires and related products.

U.S. Pat. No. 6,831,109 described a modifier for devulcanization ofcured elastomers, and especially vulcanized rubber, said modifiercontaining a first chemical substance, which is disposed towards on andthe formation of an organic cation and amine, and further containing asecond chemical substance as promoter of dissociation of the firstchemical substance, said promoter containing a functional groupconstituting an acceptor of said amine.

U.S. Pat. No. 6,541,526 describes a mechanical/chemical methodcomposition for the de-vulcanization of rubber is reported to maintainthe macromolecules in the composition and to render the sulfur thereinpassive for later re-vulcanization. This process is also reported to becost effective, environmentally friendly and to produce high qualityde-vulcanized rubber to replace virgin rubber. According to the methodof U.S. Pat. No. 6,541,526 waste rubber is shredded, crushed and metalis removed. Then the modifying composition is added as the particles ofshredded waste rubber are poured between two rollers that further crushthe particles. The modifying composition is a mixture of ingredientswhich include, by weight, the following components: (1) betweenapproximately 76% and approximately 94% of a proton donor that breakssulfur to sulfur bonds in the waste rubber; (2) between approximately 1%and approximately 5% of a metal oxide, (3) between approximately 1% andapproximately 5% of an organic acid having between 16 and 24 carbonatoms per molecule, (4) between approximately 2% and approximately 10%of a vulcanization inhibitor and (5) between approximately 2% andapproximately 10% of a friction agent.

United States Patent Application Publication No. 2010/0317752 describeda method which is reported to be effective in recycling vulcanizedelastomeric materials via a cost effective devulcanization process whichopens up or “delinks” the crosslinks of the vulcanized network structurein used vulcanized elastomers without unduly degrading the backbone ofthe rubbery polymer. This patent more specifically discloses a delinkingcomposition in the form of a combined solid dose comprising: (i) one ormore elastomer delinking accelerators selected from the group consistingof zinc salts of thiocarbamates and zinc salts of dialkyldithiophosphates; and (ii) one or more elastomer delinking acceleratorsselected from the group consisting of 2-mercaptobenzothiazole orderivatives thereof, thiurams, guanidines, 4,4′-dithiomorpholine andsulpenamides; and (iii) at least one elastomer delinking activator.However, this patent absolutely requires as essential ingredients zincsalt, an elastomer delinking accelerator and a delinking activator.

Accordingly, these foregoing patents have not proven to be commerciallyviable and the recycled rubber made by these processes have not provento be feasible for use at high loadings in demanding applications, suchas certain rubber compounds for vehicle tires. To date very littlecharacterization data has been presented to substantiate the statementsregarding the selectivity of sulfur-sulfur or sulfur-carbon bonds beingbroken instead carbon-carbon bonds within the vulcanized rubber compoundnetwork.

Cured rubber articles can also be ground into a powder and used inmanufacturing a wide variety of products. Reclaimed elastomericmaterials, such as reclaimed elastomers, ground tire rubber (GTR), andmicronized rubber powders (MRP), which include vulcanized elastomericmaterials, are used in a variety of products. For instance, micronizedrubber powders are commonly used as fillers in rubber, asphalt, andplastic articles. More specifically, micronized rubber powders arepresently being utilized as fillers in tires, industrial rubber products(hoses, power transmission belts, conveyor belts, floor mats), asphaltproducts (paving formulations and roofing shingles) and a wide array ofother products. The utilization of reclaimed elastomers in such rubberproducts is typically significantly less expensive than using virginmaterials and leads to an overall reduction in manufacturing costs. Theuse of reclaimed material is also environmentally advantageous in thatit prevents the cured rubber recovered from postconsumer and industrialsources from going to landfills or simply being burned. Finally, the useof recycled ground tire rubber and micronized rubber powders provides astrategic supply chain hedge against petroleum-based supply chain priceand supply volatility.

Today devulcanized rubber material known as reclaim exhibits excellentprocessability but poor cure properties in compounds at loadings above3-5%. Micronized rubber powder (MRP) shows acceptable cure properties,yet at higher loadings (above 5%), compound processability begins tosuffer.

Generally, ground tire rubber (GTR) consists of particle sizedistributions that range from a diameter of about 0.5 mm to about 5 mmwhich can be produced by a variety of techniques including ambienttemperature and cryogenic grinding methods. Micronized rubber powders(MRP) typically contain a significant fraction of rubber particleshaving a particle size of less than 100 microns. In any case, groundtire rubber and micronized rubber powders are commonly designated bymesh size. For example, powders in the size range of 10-30 mesh normallyare considered to be ground tire rubber while powders having a smallerparticle size which is within the range of 40-300 mesh are generallyconsidered to be micronized rubber powder. Micronized rubber powder istypically more expensive to make by virtue of requiring more processingand/or more demanding processing conditions to attain the smallerparticle size. For this reason, ground tire rubber is typically used inlow performance applications, such as floor mats, with micronized rubberpowder only being utilized in more demanding applications, such astires, where the additional cost can be justified.

The reclaimed elastomeric polymers which are used as the raw materialfor making ground tire rubber and micronized rubber powder, such asscrap tire rubber, are cured (previously vulcanized) rubbers. They areaccordingly relatively inert particles which are essentiallynon-reactive with virgin elastomers, which results in compromisedprocessing and properties at high loadings.

There has been a long-felt but unresolved need for renewed elastomercompositions which are derived from reclaimed rubber which retainuncured and cured chemical and mechanical characteristics which arevirtually the same as virgin rubber. In other words, it would be highlydesirable for such an elastomer to be capable of being processed inessentially the same way as virgin rubber and to be capable of beingsubstituted in total or at least in part for virgin rubber inmanufacturing useful products. Such a renewed rubber would optimallyexhibit physical and dynamic properties which are virtually identical tothe properties of the virgin rubber. It would also optimally have curecharacteristics and process viscosity which are similar to those of thevirgin rubber. The renewed rubber can be utilized in more demandingapplications as an elastomeric component rather than a filler, as itsproperties more closely assimilate the properties of virgin rubber.Accordingly, the renewed rubber will have greater value from a technicaland economic standpoint as it more closely mimics the curecharacteristics and physical properties of virgin rubber.

SUMMARY OF THE INVENTION

The present invention provides a method for chemically functionalizingmicronized rubber powder which is reclaimed from rubber products toprovide the renewed rubber composition with properties which mimicvirgin rubber and which can be used as the rubber for manufacturing newrubber articles. In other words, this renewed rubber can be used as therubber constituent or a part of the rubber formulation employed inmanufacturing rubber products, such as tires, hoses, power transmissionbelts, conveyor belts, and numerous other rubber articles. The renewedrubber of this invention performs the role of an uncured elastomerrather than merely serving the function of a filler.

The renewed rubber of this invention can be processed much more easilythan conventional recycled rubber compositions. It also consistentlyexhibits an array of better overall cured rubber properties with onlyminimal variations in characteristics by using feedstocks made byvarious grinding methods. In the functionalization of the renewed rubbercompositions of this invention the sulfur-sulfur bonds in micronizedrubber powder are broken to devulcanize the rubber with only a minimalnumber of carbon-carbon double bonds in the backbone of the polymerbeing broken. This allows for the renewed rubber of this invention to beused at least in part, or combined with other materials such as virginpolymers, reclaim rubber, or rubber chemicals to name a few, as therubbery component of rubber formulations (rubber compounds) that areused in manufacturing a wide array of rubber products, including tires,power transmission belts, conveyor belts, hoses, and a wide array ofother products.

The present invention more specifically discloses a method formanufacturing an environmentally friendly, chemically functionalized,renewed rubber composition having a highly desirable combination ofphysical properties and which exhibits excellent processabilitycomprising the steps of (1) blending a micronized rubber powder with aprocessing aid and functionalizing agent(s) to produce a blendedmixture; (2) processing the blended mixture under conditions of highshear and low temperature to produce a reacted mixture; (3) adding astabilizer to the reacted mixture to produce the renewed rubber.

The subject invention further reveals a chemically functionalizedrenewed rubber composition which is comprised of an elastomeric polymerand a stabilizer; wherein the rubber composition has a crosslink densitywhich is within the range of 0.05 to 2.0×10⁻⁵ mole/g, preferably in therange of 0.1 to 1.8×10⁻⁵ mole/g, and wherein the rubber composition hasa solubility fraction of less than 90 percent, preferably less than 50percent, and most preferably less than 30 percent.

The present invention also discloses a rubber composition which istypically in the form of a slab which is comprised of a micronizedrubber powder having a maximum particle size of 400 μm, preferably lessthan 200 μm, and most preferably a maximum particle size of less than100 μm, wherein the micronized rubber powder is comprised of polymericchains containing multiple double bonds in their backbones, whereinpolymeric chains within the micronized rubber powder are crosslinkedtogether with sulfur, and wherein polymeric chains within the micronizedrubber powder are functionalized with moieties of the structuralformula:

wherein n represents an integer from 1 to 10, wherein x represents aninteger from 1 to 10, and wherein y represents an integer from 1 to 10.These compositions will also typically contain a soluble fraction of therubber having soluble processing aid and polymeric chains containingmultiple double bonds in their backbones which are functionalized withmoieties having the structure illustrated above. Slabs of thisfunctionalized rubber composition easily process in internal mixers andextruders and incorporate into a rubber matrix alone or with otherpolymeric materials and compounding ingredients and fillers.

The subject invention also reveals a functionalized renewed rubbercomposition which is typically in the form of a slab which is comprisedof a micronized rubber powder having a maximum particle size of 400 μm,preferably less than 200 μm, and most preferably a maximum particle sizeof less than 100 μm, wherein the micronized rubber powder is comprisedof polymeric chains containing multiple double bonds in their backbones,wherein polymeric chains within the micronized rubber powder arecrosslinked together with sulfur, and wherein polymeric chains withinthe micronized rubber powder are functionalized with moieties of thestructural formula:

wherein n represents an integer from 1 to 10. These compositions willalso typically contain a soluble fraction of the rubber having solubleprocessing aid and polymeric chains containing multiple double bonds intheir backbones which are functionalized with moieties having thestructure illustrated above. Slabs of this functionalized rubbercomposition easily process in internal mixers and extruders andincorporate into a rubber matrix alone or with other polymeric materialsand compounding ingredients and fillers.

The functionalized renewed rubber composition of this invention can beprocessed from being in the form of a powder into the form of a slab.Accordingly, the present invention also discloses a functionalizedrenewed rubber composition which is in the form of a slab which iscomprised of a micronized rubber powder having a maximum particle sizeof 400 μm, preferably less than 200 μm, and most preferably a maximumparticle size of less than 100 μm, wherein the micronized rubber powderis comprised of polymeric chains containing multiple double bonds intheir backbones, wherein polymeric chains within the micronized rubberpowder are crosslinked together with sulfur, and wherein polymericchains within the micronized rubber powder are functionalized withmoieties of the structural formula:

wherein n represents an integer from 1 to 10. These compositions willalso typically contain a soluble fraction of the rubber having solubleprocessing aid and polymeric chains containing multiple double bonds intheir backbones which are functionalized with moieties having thestructure illustrated above. In some cases it is desirable for thefunctionalized renewed rubber compositions of this invention to befurther processed into the form of slabs. This is because slabs of thefunctionalized rubber composition can be easily process in internalmixers and extruders and incorporate into a rubber matrix alone or withother polymeric materials, compounding ingredients and/or fillers.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates the functionalization of a cured polyisoprene rubberin accordance with this invention which utilizes tetrabenzylthiuramdisulfide as the functionalizing agent.

FIG. 2 illustrates the Horikx plot for Examples 2-4.

DETAILED DESCRIPTION OF THE INVENTION

The micronized rubber powder used in the process of this invention canbe made utilizing virtually any technique which results in the powderhaving a small particle size which is typically 10 mesh or less. Themicronized rubber powder will more typically have a particle size of nomore than 30 mesh. In some applications it may be advantages to employ amicronized rubber powder having a particle size of 80 mesh, 140 mesh, oreven smaller.

In one specific embodiment of this invention the micronized rubberpowder can be made utilizing the cryogenic grinding system described inU.S. Pat. No. 7,445,170 and an impact mill as described in U.S. Pat. No.7,861,958. The teachings of U.S. Pat. No. 7,445,170 and U.S. Pat. No.7,861,958 are incorporated herein for purposes of describing usefultechniques and equipment which can be employed in making micronizedrubber power that can be employed in making renewed chemicallyfunctionalized rubber compositions in accordance with this invention.

Micronized rubber powder can also be made in many other ways other thandescribed above, such as but not limited to a wet grinding process,ambient temperature grinding process, and other cryogenic processes.Utilizing micronized rubber powder of the same material compositionmanufactured by any process in this invention will result in similarchemically functionalized materials which exhibit excellentprocessability as well as cure properties.

The rubber utilized in making the micronized rubber powder can bevirtually any kind of sulfur cured rubber compound and can come from awide variety of sources. For instance, the rubber compound can becomprise of natural rubber, synthetic polyisoprene rubber, highcis-1,4-polybutadiene rubber, medium vinyl polybutadiene rubber, highvinyl polybutadiene rubber, emulsion styrene-butadiene rubber, solutionstyrene-butadiene rubber, styrene-isoprene-butadiene rubber,styrene-isoprene rubber, butyl rubber, chlorobutyl rubber, bromobutylrubber, polynorbornene rubber, ethylene-propylene rubber (EPR),ethylene-propylene-diene rubber (EPDM), nitrile rubber, carboxylatednitrile rubber, polychloroprene rubber (neoprene rubber), polysulfiderubbers, polyacrylic rubbers, silicon rubbers, chlorosulfonatedpolyethylene rubbers, and the like as well as various mixtures thereof.

The rubber compound recovered from buffing vehicle tire treads, inrecapping procedures is one example of a source of the rubber compoundfor use in making the micronized rubber powder. However, the rubbercompound can come from a wide variety of sources including whole tirerubber, tire side walls, tire innerliners, tire carcasses, powertransmission belts, conveyor belts, hoses, and a wide variety of otherrubber products. In any case, the “rubber buffings” from tire treads arecomprised of the rubber compound, which is buffed off of the vehicletire tread in preparing the old tire carcass for being recapped. In therecapping procedure a new tread is applied to the old tire carcass andcured onto it to make the retreaded tire. In any case, such vehicle tireretread buffings are comprised predominantly of natural rubber,synthetic polyisoprene rubber, polybutadiene rubber, andstyrene-butadiene rubber. These retread buffings are typically a mixtureof natural rubber and various synthetic rubbers. Accordingly, themicronized rubber powder utilized in accordance with this invention istypically a powder of a blend of natural rubber, synthetic polyisoprenerubber, polybutadiene rubber, and styrene-butadiene rubber. However, themicronized rubber powder can be a blend of any two or more of suchrubbers or it can be comprised of only one type of rubber. For instance,the micronized rubber powder can consist solely of natural rubber,synthetic polyisoprene rubber, styrene-butadiene rubber, a blend ofnatural rubber and polybutadiene rubber, or a blend of natural rubberand styrene-butadiene rubber.

More specifically optimum properties in tire applications, especiallywear, can be obtained when the infeed material (raw starting material)used to make the micronized rubber powder matches the final rubbercompound composition. For example, using a truck tread buffing basedpredominantly on natural rubber as the starting material to makemicronized rubber powder. Then using this specific micronized rubberpowder back into truck tire applications will exhibit excellent compoundproperties. In passenger car tire applications, using predominantlystyrene-butadiene rubber compounds as the starting material tomicronized rubber powder and then using this specific micronized rubberpowder back into passenger styrene butadiene-rubber tread applicationswill exhibit excellent compound properties.

In the first step of the process of this invention the micronized rubberpowder is blended with a processing aid and a functionalizing agent toproduce a blended mixture. The processing aid will typically be added ata level which is within the range of about 1 phr (parts by weight per100 parts by weight of MRP) to about 20 phr. The processing aid willmore typically be added at a level which is within the range of about 4phr to about 15 phr and will preferably be included at a level which iswithin the range of 6 phr to 12 phr. The purpose of adding theprocessing aid is to penetrate the rubber compound and cause it to swell(wetting the surface is not sufficient). Accordingly, the processing aidis typically a low viscosity processing oil, such as a naphthenic oil, apine oil, an orange oil, or a vegetable oil, which will swell the rubberrather than simply acting as a lubricant.

The functionalizing agent is typically added at a level which is withinthe range of 0.25 phr to about 8 phr and is more typically added at alevel which is within the range of 0.5 phr to 6 phr. The functionalizingagent is preferably added at a level which is within the range of about1 phr to about 4 phr. The functionalizing agent is typically a compoundwhich acts to devulcanize the micronized rubber powder. Somerepresentative examples of functionalizing agents that can be usedinclude thiuram monosulfide, thiuram disulfide, thiuram multisulfide,tetrabenzylthiuram disulfide, cyclohexyl sulfonamide, t-butylsulfonamide, tetraalkylthiuram disulfide, tetramethylthiuram disulfide,tetraethylthiuram disulfide, dipentamethylthiuram monosulfide, andtetramethylthiuram disulfide.

Further protocols for optimization of the process of this invention tofulfill the requirements of specific applications will be apparent topersons having ordinary skill in the art. For example, in some cases todecrease material costs it will be possible to utilize a lower level ofprocessing aid while still achieving the desired objectives of thematerial. Furthermore, to increase productivity, some powders can beintroduced into a processing aid and added to the process as a solutionor slurry which would result in faster processing times. Optimization isalso needed in compound development. For example, micronized rubberpowder is currently used in typical rubber compounds over batch weight.The functionalized renewed rubber can also be used to replace rawmaterial, such as polymer or filler.

The functionalizing agent can be a compound that includes xanthategroup, such as di-alkyl xantate, sodium ethyl xanthate, potassium ethylxanthate, sodium isopropyl xanthate, sodium isobutyl xanthate, potassiumamyl xanthate, and the like. Such xanthate group containing compoundsare typically of the structural formula:

wherein R and R′ represents hydrocarbyl groups which contain from 1 to12 carbon atoms.

Thioxanthates can also be utilized as the functionalizing agent. Theycan be synthesized by reacting carbon disulfide (CS₂) with thiolatesalts. For example, sodium ethylthioxanthate (C₂H₅SCS₂Na) can be used asthe functionalizing agent in one embodiment of this invention.Dithiocarbamates are also useful as functionalizing agents in thepractice of this invention. Dithiocarbamates are made by reacting carbondisulfide with an amine. Sodium diethyldithiocarbamate (C₂H₅)₂NCS₂Na) isa representative example of the preferred dithiocarbamate that can beutilized in the practice of this invention.

Some additional representative examples of functionalizing agents thatcan be utilized in the practice of this invention includetetramethyl-2-phenylguanidine, N,N,N′,N′-trimethylguanidine,1,1,1trimethylguanidine, p-(1,3-dimethyl-3-phenylguanidino)benzoic acid,(diaminomethyleneamino) acetic acid, and 1,1,3-triethylguanidiniumchloride.

After the processing aid and the functionalizing agent are added to themicronized rubber powder it is typically advantageous to age the blendedmixture for at least 2 hours before further processing. The blendedmixture will more typically be aged for at least 4 hour and in manycases for at least 6 hours before further processing. The blendedmixture will preferably be aged for at least 8 hours and in many casesfor 12 hours to 24 hours before further processing. It is also typicallyadvantageous to mix N,N′-diphenyl guanidine into the blended mixture.

The blended mixture is then processed under conditions of high shear andlow temperature to produce a reacted mixture. During this step thereacted mixture will typically be maintained at a temperature of 70° C.or less and preferably 50° C. or less. In some cases it is advantageousto maintain the reacted mixture at a temperature of 30° C. or even aslow as 0° C. For instance, a temperature which is within the range of−20° C. to 30° C. would be highly suitable. In one embodiment of thesubject invention this is done by passing the blended mixture through amill having counter-rotating rolls which rotate at different speeds.According to some embodiments of this invention the rolls are maintainedat a temperature of 70° C. or less, preferably 50° C. or less and mostpreferably 30° C. or less while the reclaimed elastomer is subjected toshear. According to some embodiments of this invention, the rolls arespaced apart at a distance of 0.4 mm or less, typically 0.2 mm or less,and preferably 0.1 mm or less. According to some embodiments of thisinvention the rubber blend is passed through the rolls of the millmultiple times.

A stabilizer is then added to the reacted mixture to produce thechemically functionalized renewed rubber composition. The stabilizer canbe mixed into the reacted mixture using a mill mixer or an internalmixer, such as a Banbury mixer. The stabilizer will typically be addedat a level which is within the range of about 0.25 phr to about 5 phrand will more typically be added at a level which is within the range ofabout 0.5 phr to about 3 phr. The stabilizer will preferably be added ata level which is within the range of about 1 phr to about 2 phr. Thestabilizer is typically a vulcanization retarder, such asN-cyclohexyl(thio)phthalimide (CAS No. 17796-82-6).

The functionalized renewed rubber composition made by the process ofthis invention typically has a Mooney ML1+4 viscosity which is withinthe range of about 50 to 140 and which is preferably within the range of70 to 120. This functionalized renewed rubber composition is comprisedof an elastomeric polymer and a stabilizer; wherein the rubbercomposition has a crosslink density which is within the range of 0.05 to2.0×10⁻⁵ mole/g, preferably within the range of 0.1 to 1.8×10⁻⁵ mole/g,and wherein the rubber composition has a solubility fraction of lessthan 90 percent. The functionalized renewed rubber compositions of thisinvention are typically chemically functionalized in a manner wherebythe functional group is bound to the rubber by covalent bonds, ionicbonds, hydrogen bonds, and/or van der Waals forces. The elastomericpolymer is typically a polydiene rubber, such as natural rubber,polybutadiene rubber, synthetic polyisoprene rubber, styrene-butadienerubber, or a blend of any or all of these rubbers. The chemicallyfunctionalized renewed rubber compositions of this invention typicallyhave a solubility fraction of less than 50 percent and more typically ofless than of less than 30. These compositions also typically containaniline.

In one embodiment of this invention the functionalized renewed rubbercomposition is comprised of a micronized rubber powder having a maximumparticle size of 75 μm, wherein the micronized rubber powder iscomprised of polymeric chains containing multiple double bonds in theirbackbones, wherein polymeric chains within the micronized rubber powderare crosslinked together with sulfur, and wherein polymeric chainswithin the micronized rubber powder are functionalized with moieties ofthe structural formula:

wherein n represents an integer from 1 to 10, wherein x represents aninteger from 1 to 10, and wherein y represents an integer from 1 to 10.In many cases n, x, and y will represent an integer from 1 to 6 and willoften represent in integer from 1 to 4. In one embodiment of thisinvention x and y will represent the integer 1. In such cases thepolymeric chains within the micronized rubber powder will befunctionalized with moieties of the structural formula:

wherein n represents an integer from 1 to 10 and typically represents aninteger from 1 to 4. In one embodiment of this invention the micronizedrubber powder is further functionalized with moieties of the structuralformula:

wherein n represents an integer from 1 to 10 and represents an integerfrom 1 to 6. It is frequently preferred for n represents an integer from1 to 4, such as the integer 1. n represents 1. Such functionalizedrenewed rubbers are typically further comprised of a stabilizer, such asN-cyclohexyl(thio)phthalimide.

In another embodiment of this invention the functionalized renewedrubber is comprised of a micronized rubber powder having a maximumparticle size of 75 μm, wherein the micronized rubber powder iscomprised of polymeric chains containing multiple double bonds in theirbackbones, wherein polymeric chains within the micronized rubber powderare crosslinked together with sulfur, and wherein polymeric chainswithin the micronized rubber powder are functionalized with moieties ofthe structural formula:

wherein n represents an integer from 1 to 10.

In a further embodiment of this invention the functionalized renewedrubber is comprised of a micronized rubber powder having a maximumparticle size of 75 μm, wherein the micronized rubber powder iscomprised of polymeric chains containing multiple double bonds in theirbackbones, wherein polymeric chains within the micronized rubber powderare crosslinked together with sulfur, and wherein polymeric chainswithin the micronized rubber powder are functionalized with moieties ofthe structural formula:

wherein n represents an integer from 1 to 10 and more typicallyrepresents an integer from 1 to 6. It is generally preferred for n torepresents an integer from 1 to 4, such as the integer 1.

The functionalized renewed rubber formulations of this invention can bein a wide variety of physical forms. For instance, in the millingprocedures typically used, the renewed rubber formulation will generallybe in the form of a slab or a sheet. Such slabs or sheets are convenientfor utilization by manufacturer of rubber products by virtue of the factthat such sheets can be conveniently blended with other rubbers andcompounding ingredients such as antidegredants, accelerators, curatives,and the like. However, the renewed rubber composition of this inventioncan also be processed into other geometric forms which are useful forincorporation into rubber and plastic products or articles. Forinstance, in rubber applications it is typically convenient to reuse therubber formulation in the form of slabs, sheets, cubes, or hexahedrons.In the plastics industry, it is typically preferred for the renewedrubber formulation to be presented in the form of pellets, or a powder.In any case, the functionalized renewed rubber formulations of thisinvention can be processed into a geometric form of any desired size orshape. For instance, slabs of the renewed rubber formulation can bechopped into cubes, pelletized, or ground into a powder. In any case,the renewed rubber formulation will contain the functionalizedmicronized rubber powder which is formed into the desired size andshape.

Examples 1-4

In this series of experiments, a micronized rubber powder wasfunctionalized in accordance with this invention to make a chemicallyfunctionalized renewed rubber composition. In the procedure used, 200grams of micronized rubber powder which had a particle size of 30 meshwas treated in a first stage with the chemicals outlined in Tables 1 and2. This composition was allowed to sit overnight. The mixture was thenpassed through a 2-roll mill at a gap of 100 microns. The cooling systemof the 2-roll mill was set at 35° C. The composition was passed throughthe mill for several passes until the mixture became homogeneous. Oncethe composition became homogeneous, CTP was then added in the amountsoutlined in Tables 1 and 2.

TABLE 1 Amounts of functional agent, process aids, and stabilizer addedto Examples 1-3. MRP Size MRP TBzTD DPG CTP Example # (Mesh) (g) (phr)(phr) Oil (phr) (phr) 1 Aged Tire tread 0 0 0 0 2 30 200 2 0 9.1 1.5 330 200 1 3 9.1 1 TBzTDT = Tetrabenzylthiuram disulfide DPG =N,N′-diphenyl guanidine CTP = N-cyclohexyl(thio)phthalimide Oil = CrossC-100

In Example 4, an industry reference chemistry was investigated. In theprocedure used, 200 grams of micronized rubber powder which had aparticle size of 30 mesh was added to a mixture of chemicals just priorto milling. The composition of the chemicals added to the MRP isoutlined in Table 2. The mixture was then passed through a 2-roll millat a gap of 100 microns. The cooling system of the 2-roll mill was setat 55° C. The composition was passed through the mill for several passesuntil the mixture became homogeneous.

TABLE 2 Composition of chemicals added to Example 4. MRP Size MRPBenzoic Zinc Stearic Hydro- Example # (Mesh) (g) Acid oxide Acid quinoneRosin 4 - Industry 30 200 89.0% 2.0% 2.0% 4.0% 3.0% Reference

Rheology measurements, cure characteristics, and hardness were thentaken for each of the samples. MDR 2000 rheometer and Mooney Viscosityresults are shown in Table 3. Sample 1 was a fully-cured baselinematerial; therefore, rheometer results were not taken. From the resultsbelow, one skilled in the art will observe that samples 2 and 3 haveviscosities that are acceptable compared to sample 4.

TABLE 3 Cure rheology & hardness (A) results for Examples 2-4. Example #ML MH Ts1 Tc90 ML (1 + 4) Hardness 2 2.63 4.81 5.22 13.22 112 46.5 32.17 4.07 3.03 8.20 76.9 44.9 4 5.64 6.90 7.03 11.22 Off Scale (>200)59.0

A cross link density analysis was also performed on these samples. Table4 shows the overall as well as the poly-, di-, and mono-sulfidiccrosslink densities for each material. It also reports the combinedsoluble fraction of each sample extract performed in both acetone andTHF.

TABLE 4 Crosslink density analysis and soluble fraction for Examples1-4. Crosslink Density (×10⁻⁵ mole/g) Soluble Example # OverallPolysulphidic Disulphidic Monosulphidic Fraction (%) 1 3.87 (100%) 2.12(55%) 1.12 (29%) 0.63 (16%) 0 2 1.76 (100%) 0.99 (56%) 0.15 (9%)  0.62(35%) 8.5 3 1.37 (100%) 0.76 (55%) 0.61 (45%) 9.9 4 2.19 (100%) 1.25(57%) 0.44 (20%) 0.50 (23%) 5.8

By plotting the decrease in crosslink density versus the solublefraction, one can investigate if carbon-carbon bonds, sulfur-carbon, orsulfur-sulfur bonds are broken during functionalization. The crosslinkscission line on the Horikx plot is indicative of more S—C and S—S bondsthat are broken while not disturbing the C—C bonds in the polymerbackbone. The main chain scission line on the Horikx plot is moreindicative of C—C bonds being broken on the polymer backbone. See FIG. 2for the Horikx plot on Samples 2-4.

These samples were then mixed into a control compound comprised of70%/30% blend of emulsion styrene-butadiene rubber and polybutadienerubber which included carbon black as a filler using an internal mixerat a loading level of 20 weight percent. The processability and curecompound characteristics of these rubber blends were then determinedafter being cured with a standard sulfur cure package. The cure rheologyand compound properties of these rubber blends are shown in Table 5.From the data below it can be seen that the renewed rubber compositionhas better processing and properties than MRP only.

TABLE 5 Compound characteristics for 20% loading into control compoundfor Example 2 compared to MRP only and control compound. Elongation 300%Example # ML MH Ts1 Tc90 Tensile @ Break Modulus Control 1.56 15.18 4.4112.63 18.7 677 9.0 MRP only 2.34 10.84 3.45 10.76 13.0 591 6.8 (30 mesh)2 1.71 14.11 2.09 5.48 16.6 551 9.5

Examples 5-23

In this series of experiments, a micronized rubber powder wasfunctionalized in accordance with this invention to make a chemicallyfunctionalized renewed rubber composition. In the procedure used, 200grams of micronized rubber powder which had a particle size of 80 mesh(except example 22 which was 40 mesh) was treated in a first stage withthe chemicals outlined in Table 6. This composition was allowed to sitovernight. The mixture was then passed through a 2-roll mill at a gap of100 microns. The cooling system of the 2-roll mill was set at 35° C. Thecomposition was passed through the mill for several passes until themixture became homogeneous. Once the composition became homogeneous, CTPwas then added in the amounts outlined in Table 6.

TABLE 6 Chemical compositions of Examples 5-23. MRP Size TBzTD DPG Oil(type CTP Example # (Mesh) MRP (g) (phr) (phr) C-100) (phr) (phr) 5 80200 4 0 9.1 0 6 80 200 4 0 9.1 2 7 80 200 4 0 9.1 3 8 80 200 4 0 9.1 4 980 200 2 0 9.1 0 10 80 200 2 0 9.1 1 11 80 200 2 0 9.1 1.5 12 80 200 2 09.1 2 13 80 200 2 0 9.1 3 14 80 200 2 2 9.1 15 80 200 0 3 9.1 0 16 80200 2 0 4.5 1.5 17 80 200 2 0 2 1.5 18 80 200 2 0 0 1.5 19 80 200 1 09.1 1 20 80 200 1 1 9.1 1 21 80 200 1 3 9.1 1 22 40 200 2 0 9.1 0 23 80200 1 1 9.1 0

An MDR 2000 was then used to investigate rheology and curecharacteristics for each treated sample outlined above. Results for allexamples are shown in Table 7.

TABLE 7 Rheology & cure data for Examples 5-23. Example # ML MH Ts1 Tc905 4.52 11.53 1.06 3.98 6 3.43 7.70 2.08 9.77 7 3.87 7.10 4.16 13.09 83.38 6.12 8.04 17.28 9 5.33 9.68 1.11 4.02 10 4.85 7.66 2.00 9.32 114.50 6.88 1.52 12.02 12 4.49 6.41 7.59 15.05 13 4.35 5.57 15.08 16.58 143.80 6.91 2.58 11.16 15 5.17 5.51 >20 >20 16 4.88 7.56 3.46 11.21 175.48 8.37 3.29 11.47 18 5.36 8.86 2.40 11.40 19 4.98 6.12 10.91 11.62 204.13 5.34 7.37 8.99 21 3.54 4.52 >20 >20 22 4.92 6.69 6.66 12.57 23 4.247.08 0.77 2.46

These samples were then mixed into a control compound comprised of70%/30% blend of emulsion styrene-butadiene rubber and polybutadienerubber which included carbon black as a filler using a two roll mill atboth 10 weight percent and 20 weight percent loadings cure rheology isshown in Table 8. The processability and cure rheology characteristicsof these blends were then determined after being cured with a standardsulfur cure package and are reported in Table 9.

Cure rheology for the control compound used in examples 5-15 is shown inTable 9.

TABLE 8 Cure rheology for control compound used in Examples 5-15 Example# ML MH Ts1 Tc90 Control 1.52 14.63 4.41 12.58 Compound

TABLE 9 Cure rheology characteristics at 10 & 20 wt % loadings incontrol compound for examples 5-15. 10% Loading in Control 20% Loadingin Control Example # ML MH Ts1 Tc90 ML MH Ts1 Tc90 5 — — — — 1.91 17.871.63 4.47 6 — — — — 1.9 17.0 2.6 7.2 7 1.8 16.4 3.6 8.1 8 1.6 16.3 3.98.9 1.8 16.1 3.6 9.1 10 1.8 15.1 3.4 7.8 2.0 15.0 2.9 6.8 11 1.8 15.43.8 8.4 1.7 15.1 4.3 9.3 12 1.8 14.8 3.8 8.7 2.1 14.5 3.4 7.9 13 1.714.9 4.6 10.1 — — — —

Example 11 was investigated further at 10% loading in a 70/30 eSBR/PBRcarbon black control compound. Tables 10 & 11 illustrates the curedphysical properties obtained for both the control compound and thecompound containing 10% material after being cured with a standardsulfur cure package.

TABLE 10 Physical properties of control compound and MRP only vs 10%loading of Example 11. Garvey Die Extrusion Swelling Example # ML MH Ts1ML (1 + 4) & Porosity Edge Surface Corners Total Control 1.54 15.16 4.5746.4 4 4 4 4 16 MRP 2.01 14.46 3.95 55.2 4 1 3 4 12 only (80 mesh) 111.77 14.82 3.23 48.3 4 2 4 4 14

TABLE 11 Continued physical properties of control compound and MRP onlyvs 10 wt % loading of Example 11. Unaged Heat Hardness Hardness Tensile300% Build Comp. 0° C. 70° C. Abrasion Example # (A) RT (A) 70° C. MPaE@B % Mod up ° C. Set % Rebound Rebound Vol. loss Control 71 61 18.7637.2 9.4 34.6 8.2 33.4 50.5 75 MRP only 71 61 16.7 593.3 8.8 41.4 12.130.4 49.7 63 (80 mesh) 11 71 63 17.5 607.7 9.1 32.2 6.8 31.4 52.1 68

Examples 16-23 were mill mixed at 10 wt % loading into a 70/30 eSBR/PBRcarbon black control compound. After being cured with a standard sulfurcure package Cure rheology and properties are shown in Table 12.

TABLE 12 Cure rheology characteristics and properties for 10 wt %loading of Examples 16-23. RT° C. 70° C. Tensile 300% Example # Mix MLMH Ts1 Rebound Rebound MPa E@B % Mod Control Smooth 1.58 15.19 4.36 43  50.5 17.7 621 9.0 (average) 16 Very 1.89 14.10 3.73 — — — — — Rough 17Very 1.91 14.54 3.62 41.5 49.9 12.4 507 7.8 Rough 18 Very 1.95 13.993.52 — — — — — Rough 19 Rough 1.87 13.78 4.02 — — — — — 20 Smooth 1.7914.40 3.42 42.0 49.4 16.4 651 8.0 21 Smooth 1.77 15.12 2.84 41.9 49.116.9 627 8.4 22 Smooth 1.89 14.10 3.73 42.2 49.9 15.8 543 9.0 23 Rough1.85 14.44 3.30 42.0 48.7 15.9 610 8.2

Example 24

In this experiment a micronized rubber powder was functionalized inaccordance with this invention to make a chemically functionalizedrenewed rubber composition. 200 grams of micronized rubber powder whichhad a particle size of 80 mesh was treated with 3 phr MBT and 9.1 phroil and was allowed to sit overnight. The mixture was then passedthrough a 2-roll mill at a gap of 100 microns. The cooling system of the2-roll mill was set at 35° C. The composition was passed through themill for several passes until the mixture became homogeneous. Rheologyand cure results are shown in Table 13.

TABLE 13 Rheology & cure data for Example 24. Example # ML MH Ts1 Tc9024 6.59 9.48 1.85 5.95Example 24 was also mill mixed at 10 wt % loading level into a carbonblack control compound comprised of 70%/30% blend of emulsionstyrene-butadiene rubber and polybutadiene rubber. After being curedwith a standard sulfur cure package the cure rheology characteristics ofthis rubber formulation were determined and are reported in Table 14.

TABLE 14 Cure rheology characteristics for 10 wt % loading of Example 24into control compound. Example # ML MH Ts1 Tc90 Control 1.52 14.63 4.4112.58 Compound 24 1.8 14.0 2.4 7.6

Examples 25-29

In this series of experiments, a micronized rubber powder wasfunctionalized in accordance with this invention to make a chemicallyfunctionalized renewed rubber composition. In the procedure used, 200grams of micronized rubber powder which had a particle size of 80 meshwas treated in a first stage with the chemical composition outlined inTable 15. This composition was allowed to sit overnight. The mixture wasthen passed through a 2-roll mill at a gap of 100 microns. The coolingsystem of the 2-roll mill was set at 35° C. The composition was passedthrough the mill for several passes until the mixture becamehomogeneous. Once the composition became homogeneous, a stabilizer wasthen added in the amounts outlined in Table 15.

TABLE 15 Chemical compositions of Examples 25-29. MRP Oil (type ZincStearic Size MRP TBzTD DPG C-100) oxide Acid CTP Vulkalent Example #(Mesh) (g) (phr) (phr) (phr) (phr) (phr) (phr) E/C (phr) 25 80 200 2 09.1 1 1 1.5 0 26 80 200 2 0 9.1 2 2 1.5 0 27 80 200 1 0 9.1 2 2 1 0 2880 200 1 1 9.1 2 2 1 0 29 80 200 2 0 9.1 0 0 0 1.5An MDR 2000 was then used to test cure rheology characteristics for eachof these samples. Table 16 illustrates the results.

TABLE 16 Cure rheology characteristics for Examples 25-29. Example # MLMH Ts1 Tc90 25 4.2 6.7 3.9 11.7 26 4.6 6.9 4.5 11.5 27 5 6.3 7.9 11.7 283.6 5.2 4.9 9.4 29 4.7 10.8 1.2 8.0

By reviewing and comparing the information provided in Table 15 and 16it is apparent that the utilization of stearic acid and zinc oxide didnot provide a beneficial result. Accordingly, the method of thisinvention and the compositions made thereby can be prepared withoututilizing stearic acid or zinc oxide with excellent results still beingobtained. The renewed functionalized rubber compositions of thisinvention will therefore normally not contain zinc oxide or long chainfatty acids, such as stearic acid.

The renewed rubber composition of this invention can be blended with awide variety of other elastomers and elastomeric compounds to makeuseful rubber formulations which can be used in numerous applications inrubber products. These products include all types of tires includingluxury automobile tires, all season automobile tires, high performanceautomobile tires, race tires, winter tires, off the road tires,agricultural tires, mining tires, light truck tires, medium truck tires,heavy duty truck tires, earthmover tires, aircraft tires, bicycle tires,motorcycle tires, forklift truck tires, solid tires for home andindustrial applications. The renewed rubber compositions of thisinvention can also be used in a retread formulation for retreadingvirtually any type of tire such as truck tires, aircraft tires,earthmover and automobile tires. The renewed rubber compositions of thisinvention can also be used in making power transmission belts, conveyerbelts, hoses, o-rings, rings, gaskets, tracks for military, industrial,agricultural and recreational vehicles, including snow mobiles,windshield wiper blades, air springs, industrial vibration dampers. Therenewed rubber compositions of this invention can also be used in themodification of plastics and as a processing aid for fillers includingbut not limited to clay, silica, carbon black, graphene, graphite andnano-structures (including carbon nano-tubes), concrete and asphaltmodification for high performance asphalt applications. They can also beused in manufacturing a wide array of building materials such asroofing, insulation, water proofing, and pond liners.

In using the renewed rubber formulations of this invention in makinguseful rubber products, it is typically blended with one or more otherelastomeric materials at a level ranging from 1 phr to 99 phr. It willtypically be incorporated into such products at a range of 3 phr to 50phr and will more typically be incorporated at a range of 5 phr to 40phr. For instance, the renewed rubber formulation of this invention canbe incorporated into a rubbery polymer at a level which is within therange of 10 phr to 30 phr.

The renewed rubber formulation of this invention can be included inblends with natural rubber, synthetic polyisoprene rubber, emulsionstyrene butadiene rubber, solution styrene butadiene rubber, high cis1,4-polybutadiene rubber having a cis isomer content of greater than 96percent, medium vinyl polybutadiene rubber, low vinyl polybutadienerubber, high vinyl polybutadiene rubber, high trans polybutadienerubber, high trans styrene butadiene rubber and butadiene-αmethylstyrene rubber, styrene isoprene rubber, styrene isoprenebutadiene rubber, nitrile rubber, butyl rubber, carboxylated nitrilerubber, halobutyl rubber, ethylene propylene-diene monomer rubber(EPDM), ethylene-propylene rubber (EPR), hydrogenated nitrile rubber,and various blends thereof. These blends can contain 1 to 100 phr of therenewed rubber formulation of this invention. These blends can furtherbe comprised of conventional rubber reclaim and also ground tire rubber.The level of conventional rubber reclaims and ground tire rubber willtypically be in the range of 1.0 phr to 25 phr.

In tire tread formulations the renewed rubber formulation of thisinvention will typically be blended with virgin natural rubber, emulsionstyrene butadiene rubber, solution styrene butadiene rubber and/orpolybutadiene rubber at a level which is within the range of 5 to 50phr. For instance, truck tread rubber used in steer tires and drivetires may be a blend of 5 phr to 50 phr of the renewed rubberformulation of this invention with 5 to 80 phr of virgin natural rubberand 5 phr to 80 phr of emulsion styrene butadiene rubber. The trucktread rubber used in truck trailer tires can be comprised of a simpleblend of 5 phr to 50 phr of the renewed rubber formulation of thisinvention and 50 phr to 95 phr of virgin natural rubber.

Rubber formulations containing the renewed rubber of this invention canbe compounded with reinforcing silica to improve processability and toimprove the rolling resistance of tires made therewith. However, therenewed rubber of this invention can be reinforced with conventionalcarbon black fillers, starch, clay, lignin, modified lignin, graphene,modified graphene, carbon nanotubes, silica beads, talc, crosslinked geland the like.

The renewed rubber formulation of this invention can be used invirtually any component of a tire, including the tread, the sidewall,the belt, the cap ply, the apex, the bead, the chafer, the innerliner,the skim coat, the under-tread, the base, the shoulder wedge, the beltwedge, the tread cushion, the tread wings, the shoulder skirt, the plycushion, the tie gum, the rim strip, and the like. In tread rubberformulations for automobile and light truck applications, the renewedrubber will typically be blended with high cis PBD, solution SBR, and/oremulsion SBR. Such tread rubber compounds will typically contain from 5to 50 phr of the renewed rubber, 40 to 80 phr of emulsion or solutionSBR, and 5 to 50 phr of high cis polybutadiene rubber. In tire sidewallformulations the renewed rubber will typically be blended with naturalrubber and polybutadiene rubber. In tire innerliner formulations therenewed rubber will typically be blended with natural rubber, a butylrubber or a halobutyl rubber.

A tire tread compound made with the renewed rubber formulation of thisinvention can include, as a specific example, 40 phr of emulsion styrenebutadiene rubber having a bound styrene content of 19%, a mooneyviscosity of 50-65 and a glass transition temperature of −55° C., 67.50phr of carbon black masterbatch, 30 phr of high cis-polybutadienerubber, 22.73 phr of the renewed rubber formulation of this invention, 5phr of process oil, 1 phr of 40 MS plasticizer, 3 phr of phenolictackifier resin, 42.50 phr of N339 carbon black, 2.24 phr ofN-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine antidegradant, 1.12phr of 2,2,4-trimethyl-1,2-dihydroquinoline, 2.24 phr ofmicrocrystalline wax/paraffin wax blend, 3.53 phr of zinc oxidedispersion (85% ZnO), 2 phr of stearic acid, 1 phr ofN-tert-butyl-2-benzothioazolesulfenamide pellets, 0.10 phr of diphenylguanidine pellets, 2.75 phr of sulfur dispersion (80% sulfur), and 0.10phr of N-cyclohexylthio phthalimide retarder.

A specific example of a base or undertread tire formulation made withthe renewed rubber formulation of this invention can include, as aspecific example, 70 phr of natural rubber, 30 phr of highcis-polybutadiene rubber, 17.46 phr of the renewed rubber formulation ofthis invention, 2 phr of process oil (PAH<3%), 45 phr of N660 carbonblack, 2 phr of 2,2,4-trimethyl-1,2-dihydroquinoline antidegradant, 3phr of zinc oxide, 1.50 phr of stearic acid, 1.50 phr ofN-tert-butyl-2-benzothioazolesulfenamide accelerator pellets, 2 phr ofsulfur, and 0.20 phr of N-(cyclohexylthio) phthalimide retarder.

A specific example of a steel belt coat formulation made with therenewed rubber formulation of this invention can include, as a specificexample, 60 phr of natural rubber, 40 phr of high cis-polybutadienerubber, 23.24 phr of the renewed rubber formulation of this invention, 8phr of process oil, 2 phr of alkyl phenol formaldehyde novalak tackifierresin, 75 phr of N326 carbon black, 2 phr of2,2,4-trimethyl-1,2-dihydroquinoline antidegradant, 3 phr ofhexamethyloxymethyl-melamine resin, 8 phr of reinforcing resin, 3 phr ofzinc oxide, 1.50 phr of stearic acid, 1.50 phr ofN-tert-butyl-2-benzothioazolesulfenamide accelerator pellets, 5 phrsulfur, and 0.20 phr of N-(cyclohexylthio) phthalimide retarder.

A specific example of a shoulder wedge or pad formulation made with therenewed rubber formulation of this invention can include, as a specificexample, 100 phr of natural rubber, 19.13 phr of the renewed rubberformulation of this invention, 5 phr of process oil, 55 phr of N660carbon black, 1 phr of 2,2,4-trimethyl-1,2-dihydroquinolineantidegradant, 5 phr of zinc oxide, 2.50 phr of stearic acid, 0.75 phrof N-cyclohexyl-2-benzothiazole sulfenamide (CBS) accelerator, and 3 phrof sulfur.

A specific example of a belt wedge formulation made with the renewedrubber formulation of this invention can include, as a specific example,100 phr of natural rubber, 21.06 phr of the renewed rubber formulationof this invention, 2 phr of process oil (PAH<3%), 62 phr of N326 carbonblack, 2 phr of 2,2,4-trimethyl-1,2-dihydroquinoline antidegradant, 6.70phr of hexamethyloxymethyl-melamine resin, 2.50 phr of B-20-Mreinforcing resin, 7 phr of zinc oxide, 1 phr of stearic acid, 0.75 phrof benzothiazyl-2-dicyclohexyl sulfonamide (DCBS) accelerator, and 5.60phr of OT20 oil (PAH<3%).

A specific example of a tread cushion formulation made with the renewedrubber formulation of this invention can include, as a specific example,100 phr of natural rubber, 21.19 phr of the renewed rubber formulationof this invention, 8 phr of process oil (PAH<3%), 4 phr of alkyl phenolformaldehyde novalak tackifier resin, 60 phr of N326 carbon black, 1 phrof 2,2,4-trimethyl-1,2-dihydroquinoline antidegradant, 2.50 phr ofhexamethyloxymethyl-melamine resin, 1.25 phr of B-20-M reinforcingresin, 7 phr of zinc oxide, 1 phr of stearic acid, 0.50 phr ofbenzothiazyl-2-dicyclohexyl sulfonamide accelerator, and 5.50 phr ofOT20 oil (PAH<3%).

A specific example of a tread wings formulation made with the renewedrubber formulation of this invention can include, as a specific example,50 phr of natural rubber, 50 phr of high cis-polybutadiene rubber, 22.17phr of the renewed rubber formulation of this invention, 16 phr ofprocess oil, 2 phr of low molecular weight polyethylene wax, 5 phr ofalkyl phenol formaldehyde novalak tack resin, 60 phr of N660 carbonblack, 4.50 phr of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine(6PPD) antidegradant, 2 phr of 2,2,4-trimethyl-1,2-dihydroquinolineantidegradant, 2.50 phr of a microcrystalline and paraffin wax blend, 3phr of zinc oxide, 2 phr of stearic acid, 0.50 phr ofN-tert-butyl-2-benzothioazolesulfenamide accelerator pellets, and 2 phrof sulfur.

A specific example of a sidewall formulation made with the renewedrubber formulation of this invention can include, as a specific example,50 phr of natural rubber, 50 phr of high cis-polybutadiene rubber, 20.43phr of the renewed rubber formulation of this invention, 15 phr ofprocess oil, 3 phr of alkyl phenol formaldehyde novalak tack resin, 50phr of N660 carbon black, 4 phr ofN-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD) antidegradant,2 phr of 2,2,4-trimethyl-1,2-dihydroquinoline antidegradant, 2.50 phr ofmicrocrystalline and paraffin wax blend, 3 phr of zinc oxide, 2 phr ofstearic acid, 0.50 phr of N-tert-butyl-2-benzothioazolesulfenamideaccelerator pellets, and 2 phr of sulfur.

A specific example of a ply cushion formulation made with the renewedrubber formulation of this invention can include, as a specific example,60 phr of natural rubber, 40 phr of emulsion styrene-butadiene rubber,19.60 phr of the renewed rubber formulation of this invention, 10 phr ofprocess oil, 3 phr of alkyl phenol formaldehyde novalak tack resin, 55phr of N660 carbon black, 1 phr of 2,2,4-trimethyl-1,2-dihydroquinolineantidegradant, 3 phr of zinc oxide, 1 phr of stearic acid, 0.80 phr of2,2′-dibenzothiazyl disulfide, 0.10 phr of diphenyl guanadineaccelerator, and 2.50 phr of sulfur.

A specific example of a rim strip formulation made with the renewedrubber formulation of this invention can include, as a specific example,40 phr of natural rubber, 15 phr of emulsion styrene-butadiene rubber,45 phr of high cis polybutadiene rubber, 22.21 phr of the renewed rubberformulation of this invention, 15 phr of process oil, 2 phr of darkhydrocarbon resins, 3 phr of alkyl phenol formaldehyde novalak tackifierresin, 85 phr of N351 carbon black, 3 phr ofN-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD) antidegradant,1 phr of 2,2,4-trimethyl-1,2-dihydroquinoline antidegradant, 2 phr ofmicrocrystalline and paraffin wax blend, 3 phr of zinc oxide, 2 phr ofstearic acid, 0.50 phr of N-tert-butyl-2-benzothioazolesulfenamideaccelerator pellets, 1 phr of benzothiazyl-2-dicyclohexyl sulfenamideaccelerator, 2.25 phr of sulfur and 0.25 phr of N-(cyclohexylthio)phthalimide retarder.

A specific example of a rubber chafer formulation made with the renewedrubber formulation of this invention can include, as a specific example,50 phr of natural rubber, 25 phr of emulsion styrene-butadiene rubber,25 phr of high cis polybutadiene rubber, 23.49 phr of the renewed rubberformulation of this invention, 10 phr of process oil, 2 phr of darkhydrocarbon resins, 2 phr of alkyl phenol formaldehyde novalak tackifierresin, 85 phr of N326 carbon black, 2 phr of2,2,4-trimethyl-1,2-dihydroquinoline antidegradant, 1 phr ofmicrocrystalline and paraffin wax blend, 3 phr of zinc oxide, 2 phr ofstearic acid, 1.25 phr of N-tert-butyl-2-benzothioazolesulfenamideaccelerator pellets, 3 phr of sulfur and 0.2 phr of N-(cyclohexylthio)phthalimide retarder.

A specific example of an apex formulation made with the renewed rubberformulation of this invention can include, as a specific example, 65 phrof natural rubber, 35 phr of high cis polybutadiene rubber, 24.99 phr ofthe renewed rubber formulation of this invention, 10 phr of process oil,4 phr of alkyl phenol formaldehyde novalak tackifier resin, 80 phr ofN326 carbon black, 2 phr of 2,2,4-trimethyl-1,2-dihydroquinolineantidegradant, 3.5 phr of hexamethyl oxymethyl-melamine resin, 10 phr ofreinforcing resin, 5 phr of zinc oxide, 2.50 phr of stearic acid, 1.50phr of N-tert-butyl-2-benzothioazolesulfenamide accelerator pellets,6.25 phr of OT20 oil, and 0.25 phr of N-(cyclohexylthio) phthalimideretarder.

A specific example of an innerliner formulation made with the renewedrubber formulation of this invention can include, as a specific example,100 phr of chlorobutyl rubber, 24.13 phr of the renewed rubberformulation of this invention, 8 phr of process oil, 10 phr of darkhydrocarbon resins, 4 phr of alkyl phenol formaldehyde novalak tackresin, 60 phr of N660 carbon black, 30 phr of clay, 0.15 phr ofmagnesium oxide, 1 phr of zinc oxide, 2 phr of stearic acid, 1.50 phr of2,2′-debenzothiazyl disulfide, and 3 phr of sulfur.

Example 30-31

In this series of experiments a conventional tire tread compound rubber(Example 30) was prepared utilizing 10% of an 80 mesh micronized naturalrubber powder. In making this conventional tread rubber formulation, themicronized natural rubber was blended into 75 phr of solutionstyrene-butadiene rubber and 25 phr of high cis-1,4-polybutadiene rubberand cured with a conventional sulfur cure package. In this series ofexperiments another tire tread rubber formulation (Example 31) was madeby substituting a chemically functionalized, renewed natural rubbercomposition at 10% loading level. Both of the cured rubber formulationsmade in this experiment were tested for abrasion loss utilizing a ZwickRotary Drum Abrader (Din Abrasion) ASTM D 5963 Method A. The rubberformulation made utilizing the conventional micronized natural rubbershowed an abrasion loss of 105 mm³ (as compared to a conventionalstandard in accordance with procedure). However, the second rubberformulation made utilizing the a chemically functionalized, renewednatural rubber composition showed a much better abrasion loss of only 62mm³.

Example 32-33

In this series of experiments a conventional tire tread compound rubber(Example 32) was prepared utilizing 10% of emulsion styrene-butadienerubber (ESBR). In this series of experiments another tire tread rubberformulation (Example 33) was made by substituting a chemicallyfunctionalized, renewed ESBR composition at 10% loading level. Bothrubber formulations made in this experiment were tested for abrasionloss utilizing a Zwick Rotary Drum Abrader (Din Abrasion) ASTM D 5963Method A. The rubber formulation made utilizing the 10% of solution ESBRshowed an abrasion loss of 87 mm³ (as compared to a conventionalstandard in accordance with procedure). However, the second rubberformulation made utilizing the a chemically functionalized, renewed ESBRcomposition showed a much better abrasion loss of only 69 mm³.

While certain representative embodiments and details have been shown forthe purpose of illustrating the subject invention, it will be apparentto those skilled in this art that various changes and modifications canbe made therein without departing from the scope of the subjectinvention.

What is claimed is:
 1. A method for manufacturing an environmentallyfriendly, chemically functionalized, renewed rubber composition having ahighly desirable combination of physical properties and which exhibitsexcellent processability comprising the steps of (1) blending amicronized rubber powder with a processing aid and a functionalizingagent to produce a blended mixture; (2) processing the blended mixtureunder conditions of high shear and low temperature to produce a reactedmixture; and (3) adding a stabilizer to the reacted mixture to producethe renewed rubber.
 2. The method of claim 1 wherein the processingunder conditions of high shear is generated in step (2) on a 2-rollmill.
 3. The method of claim 1 wherein the functionalizing agent is acompound selected from the group consisting of alkyl thiuram sulfides,aryl thiuram sulfides, heterocyclic thiuram sulfides, thiuramdisulfides, thiuram polysulfides, thiuram disulfides, thiurammultisulfides, tetrabenzylthiuram disulfides, cyclohexyl sulfonamides,t-butyl sulfonamides, tetraalkylthiuram disulfides, tetramethylthiuramdisulfides, tetraethylthiuram disulfides, dipentamethylthiurammonosulfides, and tetramethylthiuram disulfides.
 4. The method of claim1 wherein a guanidine compound is blended into the micronized rubberpowder in step (1).
 5. The method of claim 4 wherein the guanidinecompound is selected from the group consisting of alkyl guanidines, arylguanidines, and hetrocyclic guanidines.
 6. The method of claim 1 whereinN,N′-diphenyl guanidine is blended into the micronized rubber powder instep (1).
 7. The method of claim 1 wherein the micronized rubber powderis a recycled tire rubber.
 8. The method of claim 1 wherein themicronized rubber powder is comprised of a diene rubber.
 9. The methodof claim 1 wherein the stabilizer is a vulcanization retarder andwherein the elastomeric polymer has a solubility fraction of less than30 percent.
 10. The method of claim 1 wherein the stabilizer isN-cyclohexyl(thio)phthalimide.
 11. The method of claim 1 wherein theenvironmentally friendly, chemically functionalized, renewed rubbercomposition is processed into the form of a sheet, a slab, a hexahedron,a pellet or powder.
 12. The method of claim 1 wherein the micronizedrubber powder is comprised of styrene-butadiene rubber.
 13. The methodof claim 1 wherein the micronized rubber powder is comprised of a blendof high cis-1,4-polybutadiene rubber and one or more additional rubberswherein the high cis-1,4-polybutadiene rubber has a cis-microstructurecontent of at least 95 percent.
 14. The method of claim 1 wherein themicronized rubber powder is crosslinked to a crosslink density which iswithin the range of 0.05×10⁻⁵ moles/g to 2.0×10⁻⁵ moles/g and has asoluble fraction of less than 90 percent.
 15. The method of claim 14wherein the micronized rubber powder is crosslinked to a crosslinkdensity which is within the range of 0.1×10⁻⁵ moles/g to 1.8×10⁻⁵moles/g and has a soluble fraction of less than 30 percent.
 16. Themethod of claim 1 wherein said method is conducted at a temperature ofless than 70° C.
 17. The method of claim 1 wherein the stabilizer isadded at a level which is within the range of 0.25 phr to 5 phr.
 18. Themethod of claim 1 wherein the stabilizer is added at a level which iswithin the range of 0.5 phr to 3 phr.
 19. The method of claim 1 whereinthe stabilizer is a vulcanization retarder.
 20. The functionalizedrenewed rubber composition made by the process specified in claim 1.